I like it a lot. In fact I just wrote a story with a similar mood (or theme? I always get those confused). This reminds me of the Mountains of Madness and other Lovecraftian fare. So excellent work there. My only minor nitpick is the line that makes up the fourth paragraph. In the beginning you speak about the attic, but in the fourth line you speak of the cellar which is a basement term. One of the two should be changed. Other than that great work and a good entry!
Thanks for paying attention to the minutiae of punctuation, it’s a pain but it’s something that must be inforced if one wants to make it big.
Robert Quick summarized what was in the box the best. If I were to explain it in plain words that would be a disservice to the ficlet, as it must be able to defend for itself.